Semidrying oils



Patented May 15, 1951 METHOD FOR IMPROVING DRYING AND SEMIDRYING OILS Frantisek Stejskal, near Litomerice, Czechoslovakia,

assignor to Sana,

Naro dni Podnik,

Prague, Czechoslovakia, a company of Czechoslovakia No Drawing. Application May 22, 1947, Serial No. 749,881. In Germany July 22, 1942 Section 1, Public Law '690, August 8, 1946 Patent expires July 22, 1962 11 Claims. 1

This invention relates to a method for improving drying and semi-drying oils.

Nearly all methods hitherto used for improving drying and semi-drying painting oils aim at the producing of so-called boiled oils. It is known that in this case the isolated double linkages of the linseed oil and linseed oleoacid regroup to the conjugated position owing to heating. These conjugations in the usual preparation of boiled oils are destroyed continuously and to an increasing degree by polymerization according to the principle of the Diels-Alder Dien synthesis.

According to the invention, drying and semidrying oils are heated with a catalyst until the regrouping of the double linkages of the oil to conjugated double linkages reaches a maximum, and the polymerization (thickening) a minimum. The viscosity of the improved oil scarcely differs from that of the original oil.

In almost all previous methods however the oil is converted into more or less thick liquid products owing to heating, air blasts,.chemical influences or any combination of these processes, whereat the degree of the improving generally increased with the viscosity of the improved oils at least in respect to swelling ability in water, resistance to weather, glass hardness and other properties. In order to attain a far reaching improvement of the oil e. g. (linseed oil) it must be thickened to a viscosity of about 100-200 poise.

Such products, when used for painting, need a greater thinning with solvents, such as turpentine oil, test petrol or the like. Apart from this waste of solvents, thinning has the disadvantage of diminishing the covering power and the thickness of the film of the coating, often to an undesirable extent.

It has now been found that it is possible to convert in a simple and economical manner the drying and semi-drying oils into products which do not have the above mentioned disadvantages.

It is already known to manufacture a varnish for high-speed varnishing by heating linseed oil in a special apparatus to about 280 C. (up to the commencement of polymerization) and introducing a quantity of pre-heated air, whereat the temperature rises to 300 C. and an acceleration of the polymerization takes place. By cooling, a refined boiled oil, a considerably lower viscosity than the normal boiler oil, is obtained in about two hours.

Although drying and semi-drying oils heretofore produced have only a comparatively few polymerized components, such oils did not achieve any conjugated double bonds as evidenced by the specific refraction and diene number thereof. Thus, such oils belong to a different class of refined oils from the oils produced according to the present invention, in which latter oils the conjugation of the isolated double bonds is attained to a great extent while polymerization is either largely delayed or excluded.

In the Chemisch Weekblad 1941, at pages -152 there is described a treatment of unsaturated oils with liquid sulphurous acid at 'a temperature of -220 C. and at high pressure, e. g. greater than 30 atmospheres, a conjugation of the isolated double linkages without simultaneous considerable increase in polymerization taking place. In this case, products similar to those according to the present invention are made. The older method necessitates, however, unpleasant working with liquid sulphurous acid and the acquisition and use of special pressure apparatus.

The method according to the invention is carried out, however, with the aid of metal catalysers containing sulphur, at normal pressure and at temperatures which lie below the usual boiling temperatures for boiled oil, which latter are generally higher than 270 C. The temperatures used in this case can vary according to the kind and composition of the oils and can in many cases be about 170-200 C., preferably about 180 C.

The sulphur contents of the metal catalysers containing sulphur, preferably nickel catalysers, can fluctuate in wide limits. A comparatively small sulphur content results in a perceptible action, which however, at too small quantities of sulphur, is not technically satisfactory, whereas catalysers free from sulphur are without efiect in this respect. It is preferred to work with sulphur contents of about 1-5% of the catalyser material. C

In the Journal of the Society of Chemical Industry, 1938, at pages 87-89 as described works on the polymerization of linseed oil in the presence of small quantities of sulphur or selenium. The sulphur in the given modification and at the described conditions works exactly opposite from that in the present invention, where the catalyseraccelerates only the first phase of the formation of boiled oil, viz, the conjugation of the isolated double linkage, whereas it exercises no influences on the following phase, which increases the viscosity. Thus, according to Table I of the article on oil treated for 90 minutes with 0.32% sulphur at a temperature of 290 C. possesses a density of d =0.9415 (increase, as compared with, the original oil of 0.0124 unit), a specific refraction unit) and an iodine number of 140.8 (apparent decrease of 43.2 units). The oil according to the application had in this case only a viscosity of 1.50 poise, that is it was scarcely more viscous.v

According to the invention, the catalysers can be used with or without known carriers such as kieselguhr or active carbon.

The oils treated in the presence of these catalysts show at a low viscosity and, with the addition of only small amounts of dryers, an increased drying power as well as a greatly increased bodying rate if they are subjected to further heating, when bodied oils are desired for particular purposes. In such,case, a previous separation of the catalyst is preferable but is not essential.

The films obtained with such oils are superior to the high class boiled oilfilms in respect to the ability to swell in water and are similar to wood oil films. The similarity of the oils with wood oil, to which they are related by their high cone tent of conjugated double linkages, can also be seen by the fact that the ice-flower formation known in the case of wood oil also occurs under certain circumstances at drying.

The oils improved according to the invention combine the following advantages:

1. Rapid drying power.

2. Increased polymerization ability.

3. Workability to high class films even without thinning medium.

4. High quality of the film.

5. Wood oil character as oil and film.

Nickel containing sulphur or cobalt containing sulphur can be used for example for catalysers containing sulphur.

A catalyser suitable for the method can, for example, be made somewhat a follows:

Nickel carbonate is precipitated from an aqueous solution of nickel sulphate with a sodium carbonate solution at about 80 C. and in the presence of kieselguhr. The proportion of nickel to kieselguhr may be about 2:1. The precipitated nickel carbonate is separated, boiled several times with distilled water and again separated, until the washing water is practically free from sulphate. The cake of nickel so obtained is boiled for about 3 hours with a 2% soda solution, the proportion preferably being NaCOazNi about 1:5, and then washed free from alkali.

The nickel carbonate thus obtained is boiled with a 5% solution of a fresh quantity of nickel sulphate, the proportion of the nickel content of the above mentioned nickel carbonate to the nickel content of the newly added nickel sulphate being about :1. The nickel compound is separated but not washed. The cake obtained is dried, finely ground and reduced in a hydrogen stream at about 500 C. There is then a reduction of the nickel sulphate to nickel and a reduction of the last added nickel sulphate to nickel sulphide NiS. After cooling, the hydrogen is displaced by oxygen-free C02. The catalyst is pyrophoric and therefore, as usual, kept in oil and the entrance of air is carefully avoided; preferably the used protecting'oil is of the same kind, as that for improvement of which the catalyst is designed.

The drying or semi-drying oils treated according to the present invention can be subsequently subjected to further heating to boiled oils in the filtered or unfiltered state. The heating is preferably done by running through an inert gas especially carbon dioxide.

Example 1 kilograms of refined linseed oil were mixed at 180 C., with 7 kilograms of a catalyser consisting of 60% nickel, 3% sulphur bound to nickel and 37% kieselguhr, carbon dioxide being conducted through it. After half an hour, the specific refraction was raised from 0.3068 to 0.3114, and in one hour to 0.3122. It then began to decrease again, and at the same time the viscosity increased more rapidly. Therefore it was cooled and filtered. The end product had the specific refraction of 0.3118 and the diene number 26. The viscosity was only 1.2 poise, i. e. about twice that of linseed oil.

Example 2 100 kilograms of refined linseed oil were treated as before at 200 C. with a carrier-less cobalt catalyst with a sulphur content of 5%. The maximum of the specific refraction was reached after 2 hours with 0.3110. The dienenumber was 23 and the viscosity 2.5 poise.

Example 3 100 kilograms of refined s'oya bean oil were treated with 6 kilograms of the catalyst used in Example 1 at 200 C. as there. The specific refraction had increased rapidly from 0.3054 to 0.3072. After one and a half hour treatment was stopped. The viscosity was then 0.8 poise.

Emample 4 Example 5 The same material as in Example 1 was heated to 285 C. After 5 hours a viscosity of poise/20 was reached. The catalyst was separated by filtering the oil which had a temperature of C.

I claim:

1. The method of modifying drying and semidrying oils which comprises heating the oil in the presence of a catalyst containing a small amount of sulphur combined chemically with a metal selected from the group consisting of nickel and cobalt at temperatures below that usual for polymerization until the shifting of the isolated double bonds of the oil to conjugated unsaturation reaches a maximum while the polymerization remains minimal.

2. The method of modifying drying and semidrying oils according to claim 1, wherein said temperatures are below the boiling. temperature of the oil being modified.

3. The method of modifying drying and semidrying oils according to claim.1,wherein the metal selected from said group isnickel.

4. The method of modifying drying and semidrying oils accordingto claim 3., wherein the oil is'heated to a temperature ofabout180C.

5. The method of modifying drying and semidrying oils according to claim 4, wherein said catalyst consists of 60% nickel, 3% sulphur and 37% kieselguhr.

6. The method of modifying drying and semidrying oils according to claim 1, wherein the metal selected from said group is nickel, and the oil is heated to a temperature of about 200 C.

7. The method of modifying drying and semi drying oils according to claim 1, wherein the metal Selected from said group is cobalt, and the oil is heated to a temperature of 200 C.

8. The method of modifying drying and semidrying oils according to claim 1, wherein said catalyst contains not more than 5% of sulphur.

9. The method of improving drying and semidrying oils comprising the steps of mixing the oil with a nickel catalyst having sulphur combined chemically therewith, heating the mixture to a temperature below the boiling temperature of the oil, passing an inert gas through the mixture of oil and catalyst to protect the oil and catalyst from oxidation by air, and finally removing the catalyst from the oil by filtering,

10. The method of improving drying and semidrying oils comprising the steps of mixing the oil with anickel catalyst containing sulphur combined chemically therewith, heating the mixture to a temperature below the boiling temperature of the oil, removing the catalyst from the oil by filtration, and heating the filtered oil to a tern" perature of 280-290 C. I

11. The method of improving drying and semi drying oils according to claim 10, wherein the mixture was heated to a temperature of about 180 C.

, FRANTISEK STEJSKAL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,374,589 Levey Apr. 12, 1921 2,242,230 Burr May 20, 1941 2,405,440 Marsh Aug. 6, 1946 

1. THE METHOD OF MODIFYING DRYING AND SEMIDRYING OILS WHICH COMPRISES HEATING THE OIL IN THE PRESENCE OF A CATALYST CONTAINING A SMALL AMOUNT OF SULPHUR COMBINED CHEMICALLY WITH A METAL SELECTED FROM THE GROUP CONSISTING OF NICKEL AND COBALT AT TEMPERATURES BELOW THAT USUAL FOR POLYMERIZATION UNTIL THE SHIFTING OF THE ISOLATED DOUBLE BONDS OF THE OIL TO CONJUGATED UNSATURATION REACHES A MAXIMUM WHILE THE POLYMERIZATION REMAINS MINIMAL. 